Why do fire extinguishers weigh so much?

My computer is still broken. The HDD is failing so they've ordered new parts. It's only a little over a year old, so hopefully most of it will be covered under warranty. Anyway, it's a complete bummer to be without my mini laptop, but I'm hoping they will get it fixed and sent back to me SOON! At any rate, I miss you all and hope to catch up this week. :)